1. Technical Field
Embodiments of the present invention generally relate to a developing device, a process cartridge, and an image forming apparatus, such as a copier, a printer, a facsimile machine, or a multifunction peripheral (MFP) having at least two of copying, printing, facsimile transmission, plotting, and scanning capabilities, that includes a developing device.
2. Description of the Related Art
Generally, image forming apparatuses include a developing device to develop latent images formed on a latent image bearer with developer. There are two types of developer: one-component developer including toner and two-component developer including toner and carrier. In high speed image forming apparatuses, two-component development is mainly used to secure a durability thereof. In high speed image forming apparatuses, there are demands for high image quality to cope with commercial printing.
In two-component developing devices, a range where a developing sleeve, serving as a developer bearer, faces the latent image bearer, such as a photoconductor, is called a development range. A magnetic field generator provided inside the developing sleeve generates a magnetic field that causes developer particles to stand on end, in the form of a magnetic brush, on the developing sleeve, and the magnetic brush contacts the latent image bearer in the development range. Thus, toner is supplied to the latent image on the latent image bearer, developing it into a visible image (toner image).
In this type of developing devices, toner borne on the developing sleeve moves toward the latent image bearer due to differences in surface potential between the developing sleeve, to which development voltage is applied, and the latent image bearer. Developing that uses voltage including a direct-current (DC) component is hereinafter referred to as “DC bias development”), and developing that uses voltage including an alternating-current (AC) component (i.e., a superimposed bias in which an AC component is superimposed on a DC component) is hereinafter referred to as “AC bias development”.